Positioning of vehicles and pedestrians leveraging ranging signal

ABSTRACT

A target user equipment (UE), which may be a vehicle or UE carried by a pedestrian, may receive sequentially broadcast ranging signals from a set of ranging source entities (SEs), which may be road side units or other vehicles. The target UE further receives location information separately broadcast by each SEs. The location information, for example, may include the position for the SE, the time of transmission of the ranging signals transmitted by the SE and/or a sequence identifier for the SE. The target UE may determine ranges to the SEs using time of arrival measurements for the ranging signals and the time of transmissions of the ranging signals or the sequence identifier received in the location information. The position of the target UE may be determined using the determined ranges to the SEs and the positions of the SEs received in the location information.

CLAIM OF PRIORITY UNDER 35 U.S.C. § 119

This application is a divisional of and claims priority to U.S.application Ser. No. 16/698,295, filed Nov. 27, 2019, and entitled“POSITIONING OF VEHICLES AND PEDESTRIANS LEVERAGING RANGING SIGNAL,”which is assigned to the assignee hereof and is incorporated herein byreference in its entirety.

BACKGROUND Background Field

The subject matter disclosed herein relates to wireless communicationssystems, and more particularly to methods and apparatuses for locationdetermination of a user equipment in a wireless communications system.

Relevant Background

Obtaining accurate position information for user equipment, such ascellular telephones or other wireless communication devices, is becomingprevalent in the communications industry. For example, obtaining highlyaccurate locations of vehicles or pedestrians is essential forautonomous vehicle driving and pedestrian safety applications.

A common means to determine the location of a device is to use asatellite positioning system (SPS), such as the well-known GlobalPositioning Satellite (GPS) system or Global Navigation Satellite System(GNSS), which employ a number of satellites that are in orbit around theEarth. In certain scenarios, however, location determination signalsfrom an SPS may be unavailable, e.g., in areas with poor satellitesignal reception such as tunnels or parking complexes. Moreover,position information generated using SPS is prone to imprecision. Forexample, off-the-shelf GPS positioning devices have an accuracy of a fewmeters, which is not optimal to ensure safe autonomous driving andnavigation.

To increase the accuracy of location determination it may be desirableto use signals from one or more terrestrial sources. For example,signals for determining a range to stationary roadside units or frommoving vehicles with known locations may be used by a target vehicle orpedestrian for positioning. Round trip time (RTT), for example, is atechnique commonly used for determining a position of a target vehicleor pedestrian. RTT is a two-way messaging technique in which the timebetween sending a signal from a first device to receiving anacknowledgement from a second device (minus processing delays)corresponds to the distance (range) between the two devices. While RTTis accurate, it would be desirable to reduce the power consumptionrequired by two way messaging.

SUMMARY

A target user equipment (UE), which may be a vehicle or UE carried by apedestrian, may receive sequentially broadcast ranging signals from aset of ranging source entities (SEs), which may be road side units orother vehicles. The ranging signals may be wide band signals withcontiguous or non-contiguous frequency channels. The target UE furtherreceives location information separately broadcast by each SEs. Thelocation information, for example, may include the position for the SE,the time of transmission of the ranging signals transmitted by the SEand/or a sequence identifier for the SE. The target UE may determineranges to the SEs using time of arrival measurements for the rangingsignals and the time of transmissions of the ranging signals or thesequence identifier received in the location information. The positionof the target UE may be determined using the determined ranges to theSEs and the positions of the SEs received in the location information.

In one implementation, a method of performing location determination bya user equipment (UE), includes receiving a ranging signal broadcast byeach entity in a plurality of entities in a wireless network; receivinga message with location information that is broadcast from each entityin the plurality of entities; determining a range to each entity usingthe ranging signal received from each entity and the locationinformation received from each entity; and determining a position of theuser equipment based on the range to each entity and a known location ofeach entity.

In one implementation, a user equipment (UE) configured to supportlocation determination includes a wireless transceiver configured toreceive broadcast signals from entities in a wireless network; at leastone memory; and at least one processor coupled to the wirelesstransceiver and the at least one memory, the at least one processorconfigured to: receive a ranging signal broadcast by each entity in aplurality of entities in a wireless network; receive a message withlocation information that is broadcast from each entity in the pluralityof entities; determine a range to each entity using the ranging signalreceived from each entity and the location information received fromeach entity; and determine a position of the user equipment based on therange to each entity and a known location of each entity.

In one implementation, a user equipment (UE) configured to supportlocation determination includes means for receiving a ranging signalbroadcast by each entity in a plurality of entities in a wirelessnetwork; means for receiving a message with location information that isbroadcast from each entity in the plurality of entities; means fordetermining a range to each entity using the ranging signal receivedfrom each entity and the location information received from each entity;and means for determining a position of the user equipment based on therange to each entity and a known location of each entity.

In one implementation, a non-transitory computer readable mediumincluding program code stored thereon, the program code is operable toconfigure at least one processor in a user equipment (UE) for performinglocation determination comprising program code to receive a rangingsignal broadcast by each entity in a plurality of entities in a wirelessnetwork; program code to receive a message with location informationthat is broadcast from each entity in the plurality of entities; programcode to determine a range to each entity using the ranging signalreceived from each entity and the location information received fromeach entity; and program code to determine a position of the userequipment based on the range to each entity and a known location of eachentity.

In one implementation, a method of supporting location determination ofa user equipment (UE) performed by an entity in a wireless network,includes determining an available portion of a wireless spectrum by theentity, wherein the entity is one of a plurality of ranging sources forthe UE; generating a ranging signal over the available portion of thewireless spectrum; broadcasting the ranging signal to be received by theUE; and broadcasting a message with location information related to theranging signal.

In one implementation, an entity in a wireless network capable ofsupporting location determination of a user equipment (UE) includes awireless transceiver configured to broadcast signals to a UE in awireless network; at least one memory; and at least one processorcoupled to the wireless transceiver and the at least one memory, the atleast one processor configured to: determine an available portion of awireless spectrum by the entity, wherein the entity is one of aplurality of ranging sources for the UE; generate a ranging signal overthe available portion of the wireless spectrum; broadcast the rangingsignal to be received by the UE; and broadcast a message with locationinformation related to the ranging signal.

In one implementation, an entity in a wireless network capable ofsupporting location determination of a user equipment (UE) includesmeans for determining an available portion of a wireless spectrum by theentity, wherein the entity is one of a plurality of ranging sources forthe UE; means for generating a ranging signal over the available portionof the wireless spectrum; means for broadcasting the ranging signal tobe received by the UE; and means for broadcasting a message withlocation information related to the ranging signal.

In one implementation, a non-transitory computer readable mediumincluding program code stored thereon, the program code is operable toconfigure at least one processor in an entity in a wireless network userequipment (UE) for supporting location determination of a user equipment(UE), the program code including instructions to determine an availableportion of a wireless spectrum by the entity, wherein the entity is oneof a plurality of ranging sources for the UE; generate a ranging signalover the available portion of the wireless spectrum; broadcast theranging signal to be received by the UE; and broadcast a message withlocation information related to the ranging signal.

BRIEF DESCRIPTION OF THE DRAWING

Non-limiting and non-exhaustive aspects are described with reference tothe following figures, wherein like reference numerals refer to likeparts throughout the various figures unless otherwise specified.

FIG. 1 illustrates a wireless communication system in which a targetuser equipment (UE), illustrated as a vehicle, is in wirelesscommunications with other entities in the wireless communication system.

FIG. 2 illustrates a simplified environment and an exemplary techniquefor determining a position of target UE using single-sided rangingsignals from multiple entities in a wireless communication system.

FIG. 3 illustrates an example of a call flow for a locationdetermination session with a target UE and a set of entities in awireless communication system.

FIG. 4 is a flow chart illustrating a method of performing locationdetermination by a user equipment.

FIG. 5 a flow chart illustrating a method of supporting locationdetermination of a user equipment by an entity in a wireless network.

FIG. 6 is a diagram illustrating an example of a hardware implementationof a user equipment capable of performing location using sequentiallybroadcast ranging signal broadcast.

FIG. 7 is a diagram illustrating an example of a hardware implementationof a ranging source entity capable of supporting location determinationof a user equipment using sequentially broadcast ranging signals.

DETAILED DESCRIPTION

Positioning for target vehicles or pedestrians may use single-sidedranging signals from transmitters having known positions, such asstationary roadside units (RUs) or moving vehicles that have knownpositions. Use of single-sided ranging signals reduces power consumptioncompared to conventional ranging approaches, such as round-trip-time(RTT) techniques as an acknowledgement signal is not required to betransmitted or received.

To improve ranging performance and to reduce channel access overheads,participating entities may be clustered for sequential transmissions oftheir ranging signals. The ranging signals may be a wideband waveformwith multiple contiguous or non-contiguous channels. After broadcastinga ranging signal, each entity may further broadcast a message includinglocation information, such as the entity's position, sequence ID, andtime when the ranging signal was transmitted, so that the target devicemay determine the range to the entity.

FIG. 1 illustrates a wireless communication system 100 in which a targetuser equipment (UE) 102, illustrated as a vehicle, is in wirelesscommunications with other entities 104 and 106 in the wirelesscommunication system 100. As illustrated, the target UE 102 may directlycommunicate with entity 104, which is illustrated as a road side unit(RSU) 104, using a Vehicle-to-Infrastructure (V2I) communication link105, and entity 106, which is illustrated as another vehicle 106, usinga Vehicle-to-Vehicle (V2V) communication link 107. A road side unit(RSU) is a stationary infrastructure entity, that may support V2Xapplications and that can exchange messages with other entitiessupporting V2X applications. An RSU may be a logical entity that maycombine V2X application logic with the functionality of base stations ina Radio Access Network (RAN), such as an evolved Node B (eNB) or nextgeneration evolved Node B (ng-eNB) in LTE wireless access and/or evolvedLTE (eLTE) wireless access (referred to as eNB-type RSU) or a NR Node B(gNB) in Fifth Generation (5G) wireless access, or a user equipment (UE)(referred to as UE-type RSU). The target UE 102 may communicate withadditional entities, such as additional RSUs, vehicles, or pedestrians(not shown), e.g., in a Vehicle-to-Pedestrian (V2P) communication link.

The wireless communication may be over, e.g., Proximity-based Services(ProSe) Direction Communication (PC5) reference point as defined inThird Generation Partnership Project (3GPP) Technical Specification (TS)23.303, and may use wireless communications under IEEE 1609, WirelessAccess in Vehicular Environments (WAVE), Intelligent Transport Systems(ITS), and IEEE 802.11p, on the ITS band of 5.9 GHz, or other wirelessconnections directly between entities.

For positioning of the target UE 102, the ranging sources equipment(SEs), e.g., entities 104 and 106, may transmit single-sided rangingsignals, i.e., no acknowledgement message is transmitted in response tothe ranging signal. The ranging signals, for example, may be transmittedon an unlicensed spectrum. Conventionally, transmission on an unlicensedspectrum is subject to Listen Before Talk (LBT) procedures prior totransmission. For example, typically, prior to transmission on a medium,radio transmitters are required to first sense the medium and transmitonly if the medium is sensed to be idle, sometimes referred to as clearchannel assessment (CCA). If all the SEs, e.g., RSUs 104 and vehicles106, transmit their ranging signals independently, each will beseparately required to perform LBT procedure before transmission,resulting in inefficient channel access and possibly prohibiting thedistributions of ranging signals in a timely manner.

Due to the mobility of target UE 102, which may be, e.g., a vehicle orpedestrian, as well as possible mobility of SEs, e.g., vehicle 106, themultiple ranging signals should arrive at the target UE 102 within areasonably small window of time, i.e., so that an acceptably smallamount of movement of the target UE 102 (or SE) occurs between receptionof ranging signals; otherwise the ranging performance may degrade.Furthermore, the overhead of LBT procedures scales with respect to thenumber of entities. Therefore, in order to improve ranging performanceand to reduce channel access overheads, the participating entities(i.e., SEs) are clustered for sequential transmissions of their rangingsignals.

Additionally, the unlicensed spectrum may be built of componentchannels, e.g., 80 MHz unlicensed spectrum has components of 4×20 Mhzchannels, and 2×40 Mhz channels. Other wireless nodes maybe transmittingon any of the component channels at any given time. For example, theentire 80 MHz, or one or more 20 MHz channels, or one of more 40 MHzchannels maybe occupied. In order to avoid interfering withtransmissions from other wireless nodes, the SEs may use a subset of the20 MHz component channels that are free for transmission, e.g., asdetermined by a single SE, e.g., the first or head SE in the cluster ofSEs.

The target UE 102 monitors the time of arrival (TOA) of eachsingle-sided ranging signal, but the transmission time of the rangingsignals are unknown to the target UE 102. Accordingly, in addition tobroadcasting the ranging signals, the SEs broadcast location informationthat may be used by the target UE 102 to determine the range to each SE.For example, an SE may broadcast the exact time that the ranging signalwas transmitted, which the target UE 102 may use along with the TOA ofthe ranging signal to determine the time of flight, which can beconverted to a range to the SE. Thus, the target UE 102 may monitor thechannel(s) for ranging signals all the time. Close in time to, e.g.,before or after, the broadcast of a ranging signal from an SE, each SEsends location information for its ranging signal. The locationinformation, for example, may include the time of transmission of theranging signal, the position of the SE, bandwidth used in the rangingsignal or other configuration information, etc. Using the locationinformation for the ranging signal from the SE, e.g., the time oftransmission of the ranging signal, and using the time of arrival of theranging signal measured by the target UE 102, the target UE 102 may backcalculate the time of flight of the ranging signal and, thus, the rangeto each SE.

In some implementations, the location information broadcast by one ormore SEs may include a sequence identifier for the SE in addition orinstead of the time of transmission of the ranging signal, e.g., if thelocation information is transmitted by one or more SEs beforebroadcasting the ranging signals. The sequence identifier indicates theSEs position in the sequence of broadcasts of the ranging signal fromthe cluster of SEs. The sequence identifier seq#_(i) for an SE_(i), forexample, may be used by the target UE 102 to calculate the time oftransmission of the ranging signal from that SE_(i), e.g., if the timeof transmission is not included in the location information. Forexample, the target UE 102 may be provided with the time of transmissionT₀ of the first ranging signal, e.g., in the location information fromthe first or head SE, as well as the time T_(trans) between each rangingsignal transmission. The time of transmission of any SE may then bedetermined, e.g., as T₀+(seq#_(i)*T_(trans)).

The location information broadcast by the SE may further include, e.g.,the location of the SE. Additionally, in some implementations, the SEmay further include in the location information, or in a differentmessage, a TOA of one or more ranging signals from other SEs as measuredby the SE. The location information may be transmitted by the SE in alicensed spectrum, e.g., in an Intelligent Transport Systems (ITS)spectrum.

FIG. 2 illustrates a simplified environment and an exemplary techniquefor determining a position of target UE 102 using single-sided rangingsignals from multiple entities in a wireless communication system 200.The target UE 102 may communicate wirelessly with SEs including a firstRSU 104-1, a second RSU 104-2, and another vehicle 106, which has aknown location using radio frequency (RF) signals and standardizedprotocols for the modulation of the RF signals and the exchanging ofinformation packets. By extracting different types of information fromthe exchanged signals, and utilizing the layout of the network (i.e.,the network geometry), the target UE 102 may determine its position in apredefined reference coordinate system. As shown in FIG. 2 , the targetUE 102 may specify its position (x, y) using a two-dimensionalcoordinate system; however, the aspects disclosed herein are not solimited, and may also be applicable to determining positions using athree-dimensional coordinate system, if the extra dimension is desired.Additionally, while three entities are shown in FIG. 2 , aspects mayutilize additional entities. For example, three SEs may be used todetermine a position (x, y) in a two-dimensional coordinate system,while four or more SEs may be used to determine a position (x, y, z) ina three-dimensional coordinate system. In some implementations, however,fewer than three SEs may be used, e.g., along with SPS positioning oranother positioning system, to determine a precise position of thetarget UE. For example, if the SPS positioning produces a relativelyimprecise position for the target UE, ranging signals from two SEs, or asingle SE, may be used to improve the precision of the position for thetarget UE.

In order to determine its position (x, y), the target UE 102 needs todetermine a range (distance) (dk, where k=1, 2, 3) to each entity 104-1,104-2, and 106, and the network geometry. The network geometry mayinclude the positions of each of the entities 104-1, 104-2, and 106 in areference coordinate system ((xk, yk), where k=1, 2, 3).

As illustrated, each SE 104-1, 104-2, and 106 broadcasts RF signals 201,202, and 203, respectively, that are received by the target UE 102. TheRF signals 201, 202, and 203 include the single-sided ranging signalfrom each entity 104-1, 104-2, and 106. The ranging signal, for example,may be Positioning Reference Signal (PRS) or Sounding Reference Signal(SRS) used in Long Term Evolution (LTE) as defined in 3GPP. As discussedabove, the target UE 102 may measure the TOA of the ranging signals. Theeach SE 104-1, 104-2, and 106 further broadcasts location informationwith which the target UE can determine the time of flight of the rangingsignals. For example, the location information may include the time oftransmission and/or the sequence identifier for the SE from which thetime of transmission may be determined.

Using the time of flight of the ranging signals, the distance betweenthe target UE 102 and the SEs may be determined, e.g., based on thespeed of the light. Thus, as illustrated in FIG. 2 , the range(distance) (dk, where k=1, 2, 3) to each entity 104-1, 104-2, and 106can be determined. Once each distance is determined, and the networkgeometry is known, e.g., the positions (xk, yk), where k=1, 2, 3 of eachof the entities 104-1, 104-2, and 106 is known, the target UE 102 canthen solve for its position (x, y) by using a variety of known geometrictechniques, such as, for example, trilateration. From FIG. 2 , it can beseen that the position of the target UE 102 ideally lies at the commonintersection of all of the circles 202, 204, and 206 drawn using dottedlines. Each circle being defined by radius dk and center (xk, yk), wherek=1, 2, 3. In practice, the intersection of these circles may not lie ata single point due to the noise and other errors in the networkingsystem. The network geometry, e.g., the positions (xk, yk), where k=1,2, 3 of each of the entities 104-1, 104-2, and 106, may also be providedin the broadcast location information. Using the positions of theentities 104-1, 104-2, and 106 and the intersections of the circles 202,204, and 206 around the SEs 104-1, 104-2, and 106, the position of thetarget UE 102 may be determined.

In some implementations, the single-sided ranging signals may be usedalong with other types of positioning procedures. For example, thesingle-sided ranging signals and positioning may be used with SPSpositioning. For example, if a relatively imprecise position, e.g., withan error of a few meter, has been acquired for the target UE using SPS,single sided ranging signals and positioning may be used to improve theacquired position, e.g., reducing the error to several tens ofcentimeters.

To generate the ranging signals to be used by the target UE 102, acluster or set of ranging SEs is established. For example, referring toFIG. 2 , a set of SEs may be established as the road side units 104-1,104-2 and vehicle 106. In some implementations, the set of SEs, forexample, may be capable of transmission of ranging waveforms in anunlicensed spectrum and transmission of location information in alicensed spectrum. The set of SEs, for example, may be physically neareach other. The set of SEs may be a set of one, i.e., the set mayinclude a single road side unit 104 or a single vehicle 106.

The set of SEs may include a head SE, e.g., RSU 104-1 in FIG. 2 , whichmay be arbitrarily chosen or may be chosen pursuant to predeterminedcriteria. For example, particular road side units may be given priorityas head SEs. The head SE 104-1 may be enabled to sense the receivesignal powers of channels (frequency resources) in the spectrum on whichthe ranging signals will be transmitted, which may be unlicensed. Thehead SE 104-1 detects the energy levels for the different channels inthe spectrum. The head SE 104-1 generates a wide-band ranging signal,which may be short duration, based on the detected energy levels of thedifferent channels. The ranging waveform may consist of one or moreunoccupied channels. If a channel or channels are deemed to be“occupied,” the ranging waveform is generated by puncturing the occupiedchannel(s), i.e., the ranging waveform generated without the occupiedchannels so that the ranging waveform only uses “unoccupied” or “free”channels. Thus, the ranging waveform may include multiple channels,which may be contiguous or non-contiguous. Generated ranging signals maybe transmitted on demand or may be transmitted multiple times, e.g.,periodically, by the set of SEs, where the ranging signals may have thesame configuration of channels or may have a different configuration ofchannels.

The generated ranging signal may include a preamble including anindication that the channels used in the ranging signal, and that thechannels will be occupied for a period of time, e.g., the time that itwill take for each SE in the set of SEs to sequentially transmit theirindividual ranging signals. For example, if each ranging signal is 2 mslong, and there are five SEs in the set of SEs that will sequentiallytransmit their ranging signals, the preamble may indicate that channelswill be occupied for 10 ms, or slightly longer to accommodate someadditional configuration time for the SEs to acknowledge the rangingsignals transmitted in the cluster.

Each non-head SE in the set of SEs, e.g., RSU 104-2 and vehicle 106, maybe arbitrarily assigned a sequence identifier, indicating the SEspositioning in the sequence of ranging signal transmissions. Forexample, in one implementation, the sequence of SEs may be based, inpart, on a pre-determined identity of each SE that may be assigned (orself-assigned) prior to the procedure. For example, the predeterminedidentity may be determined as Layer 2 identifier (L2 ID) mod #SEs. Byway of example, in FIG. 2 , RSU 104-2 may be assigned the secondposition, e.g., the position immediately after the head SE 104-1, andvehicle 106 may be assigned the third position. Each SE 104-2 andvehicle 106 may determine the channels to be included in the rangingwaveform from the broadcast ranging signal received from the head SE104-1 (or from any preceding SE). The SEs 104-2 and vehicle 106, forexample, may determine available channels, i.e., the portions of thewireless spectrum to be used for the ranging signal, by examining theranging waveform from a preceding SE or by examining the preamble of theranging signal from a preceding SE. Each SE 104-2 and 106 independentgenerates a ranging signal using the determined available channels. Theranging signal may be similar to PRS or SRS. In one implementation, theranging signal may also depend in part on a pre-determined identity. Forexample, the ranging signal may be a base sequence with a cyclic shiftthat is determined as L2 ID mod N, where N is the code divisionmultiplexing (CDM) factor (e.g., N=3 cyclic shifts per base sequence).Each SE 104-2 and 106 may further generate a preamble indicating thechannels used in the ranging signal and, in some implementations, theremaining time that the channels will be occupied.

Each SE in the set of SEs broadcasts its own ranging signal insequential order, based on the sequential identifier of the SE. Theranging signals, for example, may be broadcast sequentially at 160 MHzor other frequency. The ranging signals may be broadcast, for example,so that there is no temporal overlap of the ranging signals. The head SE104-1 broadcasts its ranging signal, which may include a preamble. Afterdetecting the first ranging signal from the head SE 104-1, the remainingSEs 104-2, 106 sequentially broadcast their own ranging signals, e.g.,SE 104-2 broadcasts its ranging signal immediately after receiving theranging signal from head SE 104-1, and SE 106 broadcasts its rangingsignal at a time ((Seq#)*T_(Trans)) after receiving the ranging signalfrom head SE 104-1, where Seq# is the sequence number of the SE, andT_(Trans) is the length of time to transmit each ranging signal. In someimplementations, each remaining SE 104-2, 106 may broadcast its ownranging signal immediately after receiving the ranging signal from theimmediately preceding SE, e.g., SE 104-2 broadcasts its ranging signalimmediately after receiving the ranging signal from head SE 104-1, andSE 106 broadcasts its ranging signal immediately after receiving theranging signal from SE 104-2.

Each SE in the set of SEs is further configured to broadcast locationinformation to be used by the target UE 102, including information forthe ranging signals and information for positioning, e.g., the positionof the SE. The location information may include, e.g., the position ofthe SE, the sequence identifier for the SE, and/or the exact time whenranging signal was transmitted by the SE. The location informationbroadcast by each SE (or another message broadcast by one or more SEs)may include the TOA that the SE detected ranging signals from other SEs.The location information that is broadcast from each SE may bebroadcast, e.g., in a licensed spectrum, e.g., Radio Resource Control(RRC) or Proximity-based Services (ProSe) Direction Communication (PC5)signaling protocol stack (PC5-S) in Intelligent Transport Systems (ITS)spectrum, e.g., for Vehicle to Vehicle (V2V) messages, within a specificwindow of time. For example, the location information may be broadcastwithin 10-20 ms to minimize the size of the buffer required for thetarget UE 102. The location information may be broadcast in a spectrumthat is different than that used for the ranging signals therebyavoiding interference between the ranging signals and the locationinformation.

The target UE 102 receives the sequentially broadcast ranging signalsfrom each of the SEs 104-1, 104-2, and 106 in the set of SEs. The targetUE 102 is configured to receive the separately broadcast locationinformation from each SEs 104-1, 104-2, and 106, which may be broadcastby each SE after (or before) the SE transmits its ranging signal. Thetarget UE 102 may use the received location information for each SE toanalyze the ranging signal received from the corresponding SE. Forexample, the target UE 102 may use the transmit time for the rangingsignal as indicated in the received location information and themeasured receive time of the ranging signal to determine the time offlight of the ranging signal. The time of flight may then be convertedinto the range (distance) to the SE, e.g., by the time of flight dividedby speed of light. If the transmit time for the ranging signal is notprovided, the target UE 102 may determine the transmit time based on thesequence identifier for the SE, along with the known frequency of theranging signals transmission and the time of the first transmission ofthe ranging signals, which may be provided by the head SE 104-1. Oncethe ranges to the SEs is determined, the target UE 102 may use theposition of the SEs as indicated in the received location informationalong with the determined ranges to determine the position of the targetUE 102, e.g., using trilateration. The target UE 102 may furtheraccurately derive its position by combining its relative positionutilizing the ranging signals and a determined SPS position.

In some implementations, the target UE 102 may use the TOA measured bySEs along with its own TOA measurements to generate Received Signal TimeDifference (RSTD) measurements. For example, SE 104-2 may provide, e.g.,in the location information or in a separate message, a TOA measurementfor the ranging signal that SE 104-2 received from SE 104-1, andsimilarly SE 106 may provide a TOA measurement for the ranging signalreceived by SE 106 from SE 104-1. Target UE 102 may use its own TOAmeasurements for the ranging signal from SE 104-1 to generate RSTDmeasurements. The position of the target UE 102 may accordingly bedetermined using RSTD, e.g., using Observed Time Difference of Arrival(OTDOA). For a precise position using RSTD, typically four or more SEsmay be used.

FIG. 3 illustrates an example of a call flow 300 for a locationdetermination session with UE 102 and a set of SEs including head SE104-1 and SE 104-2, and SE 106. It should be understood that the targetUE 102 may be in communication with one or more SEs prior to theinitiation of a location determination session.

As illustrated, at stage 1, the target UE 102 may send a request forranging signals to an SE, e.g., head SE 104-1, which may be a requestfor periodic ranging signals or a request for on demand ranging signals.

At stage 2, the head SE 104-1 forms a set of SEs including SE 104-2 andSE 106 and provides a request for ranging signals to the SEs in theestablished set. The head SE 104-1, for example, may be determined to bethe head SE in the set, based on previous contact with the target UE 102(at stage 1) or other mechanism, e.g., based on the ability of the SE104-1. The head SE 104-1 may provide information with which the SEs mayidentify their sequence numbers in the set of SEs, e.g., the head SE104-1 may assign the sequence number to each SE, or may provideinformation with which each SE may determine its sequence number, e.g.,head SE 104-1 may provide the number of SEs in the set and each SE maydetermine its sequence number as Layer 2 identifier (L2 ID) mod #SEs. Insome implementations, the set may include on one SE, e.g., head SE104-1.

At stage 3, the head SE 104-1 may check the availability of channels onthe spectrum to be used for the ranging signals, e.g., by detectingenergy levels for the different channels in the spectrum to determine ifchannels are occupied or free. The head SE 104-1 generates a rangingsignal, e.g., using unoccupied or free channels and generates a preambleidentifying the used channels and reserving the used channels for theduration of the sequential broadcast of ranging signals from the SEs.

At stage 4, the head SE 104-1 broadcasts the ranging signal, which isreceived by the target UE 102, as well as the other SEs in the set ofSEs, i.e., SE 104-2 and SE 106. The ranging signal, which may be, e.g.,a PRS or SRS signal, may be transmitted on an unlicensed spectrum, andmay be a wide band signal using contiguous or non-contiguous channels.The target UE 102 measures the TOA of the ranging signal from the headSE 104-1.

At stage 5, the next SE 104-2 in the set of SEs determines the availablechannels in the spectrum, e.g., by detecting the channels used or thechannels identified in the preamble of the ranging signal received atstage 4. The SE 104-2 generates a ranging signal using the availablechannels.

At stage 6, the SE 104-2 broadcasts the ranging signal, which isreceived by the target UE 102, as well as the other SEs in the set ofSEs, i.e., SE 106. The ranging signal, which may be, e.g., a PRS or SRSsignal, may be transmitted on an unlicensed spectrum, and may be a wideband signal using contiguous or non-contiguous channels. The target UE102 measures the TOA of the ranging signal from the SE 104-2.

At stage 7, the next SE 106 in the set of SEs determines the availablechannels in the spectrum, e.g., by detecting the channels used or thechannels identified in the preamble of the ranging signal received atstage 4 or stage 6. The SE 106 generates a ranging signal using theavailable channels.

At stage 8, the SE 106 broadcasts the ranging signal, which is receivedby the target UE 102, as well as any other SEs that may be included inthe set of SEs, (not shown in FIG. 3 ). The ranging signal, which maybe, e.g., a PRS or SRS signal, may be transmitted on an unlicensedspectrum, and may be a wide band signal using contiguous ornon-contiguous channels. The target UE 102 measures the TOA of theranging signal from the SE 106.

At stage 9, the head SE 104-1 broadcasts the location information for SE104-1, which is received by target UE 102. The location information maybe transmitted on a licensed spectrum, such as an ITS spectrum. Thelocation information may include, e.g., the position of the SE 104-1,the sequence identifier for the SE 104-1, the exact time when rangingsignal was transmitted by the SE 104-1.

At stage 10, the SE 104-2 broadcasts the location information for SE104-2, which is received by target UE 102. The location information maybe transmitted on a licensed spectrum, such as an ITS spectrum. Thelocation information may include, e.g., the position of the SE 104-2,the sequence identifier for the SE 104-2, the exact time when rangingsignal was transmitted by the SE 104-2. The location information mayfurther include the TOA of the ranging signal from head SE 104-1detected by SE 104-2 at stage 4.

At stage 11, the SE 106 broadcasts the location information for SE 106,which is received by target UE 102. The location information may betransmitted on a licensed spectrum, such as an ITS spectrum. Thelocation information may include, e.g., the position of the SE 106, thesequence identifier for the SE 106, the exact time when ranging signalwas transmitted by the SE 106. The location information may furtherinclude the TOA of the ranging signal from head SE 104-1 and/or SE 104-2detected by SE 106 at stage 4 and/or stage 6.

At stage 12, the target UE 102 determines the range to each SE 104-1,104-2, and 106. The target UE 102, for example, may use the TOA of theranging signals measured at stages 4, 6, and 8 and the time oftransmissions received in the location information at stages 9, 10, and11 to determine the time of flight of each ranging signal which can beconverted to a range (distance) to each SE 104-1, 104-2, and 106. Insome implementations, TOA measurements by the target UE 102 and the timeof transmissions from the SEs may be synchronized, e.g., using RTTmethod or may be estimated based on a Kalman filter. The target UE 102may use the sequence identifier provided in location information atstages 9, 10, and 11, along with the frequency of the ranging signaltransmissions and time of transmission of the ranging signal from thehead SE 104-1 (which may be included in the preamble of ranging signalat stage 4 or in the location information received at stage 9) todetermine the time of transmission of each ranging signal from SEs 104-2and 106. In another implementation, the target UE 102 may use the TOAsfor ranging signals measured by SEs as provided in location informationat stages 9, 10, and 11 along with the TOAs measured by target UE 102 atstages 4, 6, and 8 to determine relative ranging signals, e.g., RSTD.

At stage 13, the target UE 102 may use the ranges determined at stage12, along with the positions of the SEs 104-1, 104-2, and 106, receivedin the location information at stages 9, 10, and 11 to estimate theposition of the target UE 102, e.g., using trilateration or otherappropriate techniques. In some implementations, the target 102 may usethe ranges determined at stage 12, along with the positions of the SEs104-1, 104-2, and 106, received in the location information at stages 9,10, and 11 to estimate a relative position of the target UE 102 whichmay be combined with a measured SPS position to derive an accurateposition for the target UE 102.

FIG. 4 is a flow chart illustrating a method of performing locationdetermination by a user equipment (UE), such as a target UE 102 show inFIGS. 1, 2, and 3 . As illustrated in block 402, a ranging signalbroadcast by each entity in a plurality of entities in a wirelessnetwork is received, e.g., as discussed at stages 4, 6, and 8 shown inFIG. 3 . At block 404, a message with location information that isbroadcast from each entity in the plurality of entities is received,e.g., as discussed at stages 9, 10, and 11 shown in FIG. 3 . The messagewith the location information, for example, may be broadcast at adifferent time than the ranging signal. At block 406, a range to eachentity is determined using the ranging signal received from each entityand the location information received from each entity, as discussed atstage 12 shown in FIG. 3 . At block 408, a position of the userequipment is determined based on the range to each entity and a knownlocation of each entity, e.g., as discussed at stage 13 shown in FIG. 3.

In one implementation, the plurality of entities comprise a cluster ofentities that sequentially broadcast ranging signals, e.g., as discussedat stages 4, 6, and 8 shown in FIG. 3 . For example, the sequentiallybroadcast ranging signals may be broadcast with no temporal overlap andusing a same set of channels. A first ranging signal in the sequentiallybroadcast ranging signals may include an identification of the set ofchannels in a preamble that is determined by a first entity in thecluster of entities.

In one implementation, each ranging signal broadcast by each entity is awideband waveform comprising multiple channels. The multiple channelsmay be contiguous or the multiple channels may not be contiguous.

In one implementation, each entity in the plurality of entitiescomprises one of a road side unit or a vehicle.

In one implementation, each message with the location information isreceived from each entity in an Intelligent Transport System (ITS)spectrum.

In one implementation, the location information broadcast by an entitymay include at least one of the known location of the entity, a sequenceidentifier indicating a position of the entity in sequentiallybroadcasting the ranging signals, a time when the entity broadcast theranging signal, or a combination thereof. In one implementation, foreach entity, determining the range to the entity may use a time aranging signal is received from the entity and the time when the entitybroadcast the ranging signal received in the location information fromthe entity. In one implementation, for each entity, determining the timewhen the entity broadcast the ranging signal may use the sequenceidentifier received in the location information from the entity, anddetermining the range to the entity uses a time a ranging signal isreceived from the entity and the time when the entity broadcast theranging signal determined using the sequence identifier.

FIG. 5 is a flow chart illustrating a method of supporting locationdetermination of a user equipment (UE), such as target UE 102 shown inFIGS. 1, 2, and 3 , performed by an entity in a wireless network, suchas head SE 104-1 or SEs 104-2, 106 shown in FIGS. 1, 2, and 3 . Asillustrated at block 502, an available portion of a wireless spectrum isdetermined by the entity, wherein the entity is one of a plurality ofranging sources for the UE, e.g., as discussed at stages 3, 5, and 7shown in FIG. 3 . At block 504, a ranging signal is generated over theavailable portion of the wireless spectrum, e.g., as discussed at stages3, 5, and 7 shown in FIG. 3 . At block 506, the ranging signal to bereceived by the UE is broadcast, e.g., as discussed at stages 4, 6, and8 shown in FIG. 3 . At block 508, a message with location informationrelated to the ranging signal is broadcast, e.g., as discussed at stages9, 10, and 11 shown in FIG. 3 . The message with the locationinformation may be broadcast at a different time than the rangingsignal.

In one implementation, the ranging signal is a wideband waveformcomprising multiple channels. The multiple channels may be contiguous orthe multiple channels may not be contiguous.

In one implementation, the plurality of ranging sources for the UEcomprise a cluster of ranging sources that sequentially broadcastranging signals. In one implementation, the sequentially broadcastranging signals are broadcast with no temporal overlap and using a sameset of channels. In one implementation, a first ranging signal in thesequentially broadcast ranging signals includes an identification of theset of channels in a preamble that is determined by a first rangingsource in the cluster of ranging sources. In one implementation, forexample, the entity may be a first ranging source in the plurality ofranging sources that sequentially broadcast ranging signals. In thisexample, the available portion of the wireless spectrum may bedetermined by detecting an energy level for different channels in thewireless spectrum, e.g., as discussed at stage 3 shown in FIG. 3 . Inthis example, the ranging signal includes generating a preambleindicating a time over which the sequentially broadcast ranging signalswill occur. In one implementation, for example, the entity broadcaststhe ranging signal after receiving a ranging signal broadcast by aranging source that immediately precedes the entity in the sequentialbroadcast of the ranging signals, e.g., as discussed at stage 5, 6 and7, 8 shown in FIG. 3 . In this example, the available portion of thewireless spectrum is determined by examining a waveform or a preamble ofa ranging signal from a preceding ranging source, e.g., as discussed atstages 5 and 7 shown in FIG. 3 .

In one implementation, the message with the location information relatedto the ranging signal may be broadcast in an Intelligent TransportSystem (ITS) spectrum.

In one implementation, the location information may include at least oneof a location of the entity, a sequence identifier indicating a positionof the entity in the plurality of ranging sources for the UE, a timewhen the entity broadcast the ranging signal, or a combination thereof.

In one implementation, the entity may be a road side unit or a vehicle.

FIG. 6 is a diagram illustrating an example of a hardware implementationof a UE 600 capable of performing location using sequentially broadcastranging signal as discussed herein. The UE 600, for example, may be thetarget UE 102 shown in FIGS. 1, 2, 3 , and may be part of a vehicle or apedestrian. The UE 600 includes a Wireless Wide Area Network (WWAN)transceiver 620, including a transmitter and receiver, such as acellular transceiver, configured to receive PRS from base stations orSRS type ranging signals from other UEs, e.g., in vehicles or onpedestrians in the wireless network. The WWAN transceiver 620 may alsobe configured to wirelessly communicate directly with one or moreranging source entities (SEs) such as road side units and vehicles andto receive sequentially broadcast ranging signals and broadcast locationinformation, e.g., using wireless communications under IEEE 802.11p onthe ITS band of 5.9 GHz or other appropriate short range wirelesscommunications. The UE 600 may further include a Wireless Local AreaNetwork (WLAN) transceiver 610, including a transmitter and receiver,which may also be used to wirelessly communicate directly with otherentities, and in some embodiments with ranging source entities. The UE600 may further include an SPS receiver 630 with which SPS signals fromSPS satellites, e.g., GPS or GNSS, may be received. The UE 600 mayinclude additional features, such as user interface 640 that may includee.g., a display, a keypad or other input device, such as virtual keypadon the display, through which the user may interface with the UE 600.

The UE 600 further includes one or more processors 650 and memory 660,which may be coupled together with bus 602. The one or more processors650 and other components of the UE 600 may similarly be coupled togetherwith bus 602, a separate bus, or may be directly connected together orcoupled using a combination of the foregoing. The memory 660 may containexecutable code or software instructions that when executed by the oneor more processors 650 cause the one or more processors 650 to operateas a special purpose computer programmed to perform the techniquesdisclosed herein. As illustrated in FIG. 6 , the memory 660 may includeone or more components or modules that may be implemented by the one ormore processors 650 to perform the methodologies described herein. Whilethe components or modules are illustrated as software in memory 660 thatis executable by the one or more processors 650, it should be understoodthat the components or modules may be dedicated hardware either in theone or more processors 650 or off the processors.

The memory 660 may include ranging signal module 662 that whenimplemented by the one or more processors 650 configures the one or moreprocessors 650 to cause the WWAN transceiver 620 to directly receivesequentially broadcast ranging signals from a set of SEs and to measurethe TOA of each ranging signal from each SE, e.g., as discussed atstages 4, 6, and 8 in FIG. 3 and block 402 in FIG. 4 .

Memory 660 may further include a location information module 664 thatwhen implemented by the one or more processors 650 configures the one ormore processors 650 to cause the WWAN transceiver 620 to directlyreceive a message with location information that is broadcast from eachentity in the plurality of entities, e.g., as discussed at stages 9, 10,and 11 in FIG. 3 and block 404 in FIG. 4 . In some implementations, thelocation information may be broadcast over a different spectrum, e.g., alicensed spectrum, than the spectrum used for the ranging signals, e.g.,an unlicensed spectrum, although in some implementations, the locationinformation and ranging signals may broadcast on the same spectrum. Thelocation information for example, may include at least one of a locationof the entity, a sequence identifier indicating a position of the entityin sequentially broadcasting of the ranging signals, a time when theentity broadcast the ranging signal, or a combination thereof.

Memory 660 may further include a location determination module 668 thatwhen implemented by the one or more processors 650 configures the one ormore processors 650 to estimate a position of the UE 600. For example,location determination module 668 may include a ranging module 670 thatwhen implemented by the one or more processors 650 configures the one ormore processors 650 to determine a range to each entity using theranging signal received from each entity and the location informationreceived from each entity, e.g., as discussed at stages 12 in FIG. 3 andblock 406 in FIG. 4 . For example, the range may be determined using atime a ranging signal is received from the entity and the time when theentity broadcast the ranging signal as received in the locationinformation from the entity. In another example, the range may bedetermined by determining the time when the entity broadcast the rangingsignal using the sequence identifier received in the locationinformation from the entity, and then determining the range to theentity using a time a ranging signal is received from the entity and thetime when the entity broadcast the ranging signal determined using thesequence identifier.

The location determination module 668 may also include a positioningmodule 672 that when implemented by the one or more processors 650configures the one or more processors 650 to determine a position of theuser equipment 600 based on the range to each entity and a knownlocation of each entity, e.g., as discussed at stages 13 in FIG. 3 andblock 408 in FIG. 4 . For example, the positioning module 672 mayconfigure the one or more processors 650 to determine the position ofthe user equipment 600 using trilateration based on the ranges to theentities and their positions as received in the location information.The positioning module 672 may further configure the one or moreprocessors 650 to determine the position of the user equipment 600 usingSPS signals 630 with the ranges to the entities and their positions asreceived in the location information.

Additionally, memory 660 may further include a transmission time module666 that when implemented by the one or more processors 650 configuresthe one or more processors 650 to determine the time when the entitybroadcast the ranging signal using the sequence identifier received inthe location information from the entity, e.g., as discussed at stage 12in FIG. 3 .

The methodologies described herein may be implemented by various meansdepending upon the application. For example, these methodologies may beimplemented in hardware, firmware, software, or any combination thereof.For a hardware implementation, the one or more processors 650 may beimplemented within one or more application specific integrated circuits(ASICs), digital signal processors (DSPs), digital signal processingdevices (DSPDs), programmable logic devices (PLDs), field programmablegate arrays (FPGAs), processors, controllers, micro-controllers,microprocessors, electronic devices, other electronic units designed toperform the functions described herein, or a combination thereof.

For an implementation of UE 600 involving firmware and/or software, themethodologies may be implemented with modules (e.g., procedures,functions, and so on) that perform the separate functions describedherein. Any machine-readable medium tangibly embodying instructions maybe used in implementing the methodologies described herein. For example,software codes may be stored in a memory (e.g. memory 660) and executedby one or more processors 650, causing the one or more processors 650 tooperate as a special purpose computer programmed to perform thetechniques disclosed herein. Memory may be implemented within the one orprocessors 650 or external to the one or more processors 650. As usedherein the term “memory” refers to any type of long term, short term,volatile, nonvolatile, or other memory and is not to be limited to anyparticular type of memory or number of memories, or type of media uponwhich memory is stored.

If implemented in firmware and/or software, the functions performed byUE 600 may be stored as one or more instructions or code on anon-transitory computer-readable storage medium such as memory 660.Examples of storage media include computer-readable media encoded with adata structure and computer-readable media encoded with a computerprogram. Computer-readable media includes physical computer storagemedia. A storage medium may be any available medium that can be accessedby a computer. By way of example, and not limitation, suchcomputer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or otheroptical disk storage, magnetic disk storage, semiconductor storage, orother storage devices, or any other medium that can be used to storedesired program code in the form of instructions or data structures andthat can be accessed by a computer; disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and Blu-ray disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Combinations of the above should also be included within the scope ofcomputer-readable media.

In addition to storage on computer-readable storage medium, instructionsand/or data for UE 600 may be provided as signals on transmission mediaincluded in a communication apparatus. For example, a communicationapparatus comprising part or all of UE 600 may include a transceiverhaving signals indicative of instructions and data. The instructions anddata are stored on non-transitory computer readable media, e.g., memory660, and are configured to cause the one or more processors 650 tooperate as a special purpose computer programmed to perform thetechniques disclosed herein. That is, the communication apparatusincludes transmission media with signals indicative of information toperform disclosed functions. At a first time, the transmission mediaincluded in the communication apparatus may include a first portion ofthe information to perform the disclosed functions, while at a secondtime the transmission media included in the communication apparatus mayinclude a second portion of the information to perform the disclosedfunctions.

Thus, a user equipment, such as UE 600, may include a means forreceiving a ranging signal broadcast by each entity in a plurality ofentities in a wireless network, which may be, e.g., the WWAN transceiver620 and one or more processors 650 with dedicated hardware orimplementing executable code or software instructions in memory 660 suchas the ranging signal module 662. A means for receiving a message withlocation information that is broadcast from each entity in the pluralityof entities may be, e.g., the WWAN transceiver 620 and one or moreprocessors 650 with dedicated hardware or implementing executable codeor software instructions in memory 660 such as the location informationmodule 664. A means for determining a range to each entity using theranging signal received from each entity and the location informationreceived from each entity may be, e.g., the one or more processors 650with dedicated hardware or implementing executable code or softwareinstructions in memory 660 such as the ranging module 670. A means fordetermining a position of the user equipment based on the range to eachentity and a known location of each entity may be, e.g., the one or moreprocessors 650 with dedicated hardware or implementing executable codeor software instructions in memory 660 such as the positioning module672.

The user equipment may further include a means for determining the timewhen the entity broadcast the ranging signal using a sequence identifierreceived in the location information from the entity, which may be,e.g., the transmission time module 666.

FIG. 7 is a diagram illustrating an example of a hardware implementationof a ranging source entity (SE) 700 capable of supporting locationdetermination of a user equipment (UE) using sequentially broadcastranging signals as discussed herein. By way of example, the SE 700 maybe a stationary entity, such as a road side unit, but alternatively maybe a non-stationary entity, such as a vehicle, with a known position.The SE 700 includes a Wireless Wide Area Network (WWAN) transceiver 720,including a transmitter and receiver, such as a cellular transceiver,configured to wirelessly communicate directly with and broadcast rangingsignals and location information to target UEs, e.g., using wirelesscommunications under IEEE 802.11p on the ITS band of 5.9 GHz or otherappropriate short range wireless communications. The SE 700 may furtherinclude a Wireless Local Area Network (WLAN) transceiver 710, includinga transmitter and receiver, which may also be used to wirelesslycommunicate directly with other entities, and in some embodiments withUEs. The SE 700 may further include an SPS receiver 730 with which SPSsignals from SPS satellites may be received and used to determine theposition of the SE 700.

The SE 700 further includes one or more processors 740 and memory 750,which may be coupled together with bus 702. The one or more processors740 and other components of the SE 700 may similarly be coupled togetherwith bus 702, a separate bus, or may be directly connected together orcoupled using a combination of the foregoing. The memory 750 may containexecutable code or software instructions that when executed by the oneor more processors 740 cause the one or more processors 740 to operateas a special purpose computer programmed to perform the techniquesdisclosed herein. As illustrated in FIG. 7 , the memory 750 may includeone or more components or modules that may be implemented by the one ormore processors 740 to perform the methodologies described herein. Whilethe components or modules are illustrated as software in memory 750 thatis executable by the one or more processors 740, it should be understoodthat the components or modules may be dedicated hardware either in theone or more processors 740 or off the processors.

The memory 750 may include a channel availability module 752 that whenimplemented by the one or more processors 740 configures the one or moreprocessors 740 to use WWAN transceiver 720 to determine an availableportion of a wireless spectrum by the entity, wherein the entity is oneof a plurality of ranging sources for the UE, e.g., as discussed atstages 3, 5, and 7 of FIG. 3 and block 502 of FIG. 5 . For example, theavailable portion of the wireless spectrum may be determined bydetecting energy level for different channels in the wireless spectrumas received by WWAN transceiver 720. In another example, the availableportion of the wireless spectrum may be determined by examining awaveform or a preamble of a ranging signal from a preceding rangingsource.

The memory 750 may include a ranging signal generation module 754 thatwhen implemented by the one or more processors 740 configures the one ormore processors 740 to generate a ranging signal over the availableportion of the wireless spectrum, e.g., as discussed at stages 3, 5, and7 of FIG. 3 and block 504 of FIG. 5 . The ranging signal may be awideband waveform with multiple channels, which may be contiguous or notcontiguous. The one or more processors 740 may be configured to generatethe ranging signal to include a preamble that indicates a time overwhich sequentially broadcast ranging signals will occur, e.g., asdiscussed at stages 3 of FIG. 3 .

The memory 750 may include a ranging signal transmission module 756 thatwhen implemented by the one or more processors 740 configures the one ormore processors 740 to use WWAN transceiver 720 to broadcast the rangingsignal to be received by the UE, e.g., as discussed at stages 4, 6, and8 of FIG. 3 and block 506 of FIG. 5 . The ranging signal, for example,may be broadcast over an unlicensed spectrum. The broadcast of theranging signals may be part of sequential broadcasts of ranging signalsby a plurality of SEs in a set of SEs, where the ranging signal isbroadcast after receiving a ranging signal broadcast by a ranging sourcethat immediately precedes the entity in the sequential broadcast of theranging signals.

The memory 750 may include a location information transmission module758 that when implemented by the one or more processors 740 configuresthe one or more processors 740 to use WWAN transceiver 720 to broadcasta message with location information related to the ranging signal, e.g.,as discussed at stages 9, 10, and 11 of FIG. 3 and block 508 of FIG. 5 .The location information, for example, may be broadcast in anIntelligent Transport System (ITS) spectrum. The location informationmay include at least one of a location of the entity, a sequenceidentifier indicating a position of the entity in the plurality ofranging sources for the UE, a time when the entity broadcast the rangingsignal, or a combination thereof.

The methodologies described herein may be implemented by various meansdepending upon the application. For example, these methodologies may beimplemented in hardware, firmware, software, or any combination thereof.For a hardware implementation, the one or more processors 740 may beimplemented within one or more application specific integrated circuits(ASICs), digital signal processors (DSPs), digital signal processingdevices (DSPDs), programmable logic devices (PLDs), field programmablegate arrays (FPGAs), processors, controllers, micro-controllers,microprocessors, electronic devices, other electronic units designed toperform the functions described herein, or a combination thereof.

For an implementation of SE 700 involving firmware and/or software, themethodologies may be implemented with modules (e.g., procedures,functions, and so on) that perform the separate functions describedherein. Any machine-readable medium tangibly embodying instructions maybe used in implementing the methodologies described herein. For example,software codes may be stored in a memory (e.g. memory 750) and executedby one or more processors 740, causing the one or more processors 740 tooperate as a special purpose computer programmed to perform thetechniques disclosed herein. Memory may be implemented within the one orprocessors 740 or external to the one or more processors 740. As usedherein the term “memory” refers to any type of long term, short term,volatile, nonvolatile, or other memory and is not to be limited to anyparticular type of memory or number of memories, or type of media uponwhich memory is stored.

If implemented in firmware and/or software, the functions performed bySE 700 may be stored as one or more instructions or code on anon-transitory computer-readable storage medium such as memory 750.Examples of storage media include computer-readable media encoded with adata structure and computer-readable media encoded with a computerprogram. Computer-readable media includes physical computer storagemedia. A storage medium may be any available medium that can be accessedby a computer. By way of example, and not limitation, suchcomputer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or otheroptical disk storage, magnetic disk storage, semiconductor storage, orother storage devices, or any other medium that can be used to storedesired program code in the form of instructions or data structures andthat can be accessed by a computer; disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and Blu-ray disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Combinations of the above should also be included within the scope ofcomputer-readable media.

In addition to storage on computer-readable storage medium, instructionsand/or data for SE 700 may be provided as signals on transmission mediaincluded in a communication apparatus. For example, a communicationapparatus comprising part or all of SE 700 may include a transceiverhaving signals indicative of instructions and data. The instructions anddata are stored on non-transitory computer readable media, e.g., memory750, and are configured to cause the one or more processors 740 tooperate as a special purpose computer programmed to perform thetechniques disclosed herein. That is, the communication apparatusincludes transmission media with signals indicative of information toperform disclosed functions. At a first time, the transmission mediaincluded in the communication apparatus may include a first portion ofthe information to perform the disclosed functions, while at a secondtime the transmission media included in the communication apparatus mayinclude a second portion of the information to perform the disclosedfunctions.

Thus, a SE, such as SE 700, may include a means for determining anavailable portion of a wireless spectrum by the entity, wherein theentity is one of a plurality of ranging sources for the UE, which maybe, e.g., the WWAN transceiver 720 and one or more processors 740 withdedicated hardware or implementing executable code or softwareinstructions in memory 750 such as the channel availability module 752.A means for generating a ranging signal over the available portion ofthe wireless spectrum may be, e.g., the one or more processors 740 withdedicated hardware or implementing executable code or softwareinstructions in memory 750 such as the ranging signal generation module754. A means for broadcasting the ranging signal to be received by theUE may be, e.g., the WWAN transceiver 720 and one or more processors 740with dedicated hardware or implementing executable code or softwareinstructions in memory 750 such as the ranging signal broadcast module756. A means for broadcasting a message with location informationrelated to the ranging signal may be, e.g., the WWAN transceiver 720 andone or more processors 740 with dedicated hardware or implementingexecutable code or software instructions in memory 750 such as thelocation information broadcast module 758.

Reference throughout this specification to “one example”, “an example”,“certain examples”, or “exemplary implementation” means that aparticular feature, structure, or characteristic described in connectionwith the feature and/or example may be included in at least one featureand/or example of claimed subject matter. Thus, the appearances of thephrase “in one example”, “an example”, “in certain examples” or “incertain implementations” or other like phrases in various placesthroughout this specification are not necessarily all referring to thesame feature, example, and/or limitation. Furthermore, the particularfeatures, structures, or characteristics may be combined in one or moreexamples and/or features.

Some portions of the detailed description included herein are presentedin terms of algorithms or symbolic representations of operations onbinary digital signals stored within a memory of a specific apparatus orspecial purpose computing device or platform. In the context of thisparticular specification, the term specific apparatus or the likeincludes a general purpose computer once it is programmed to performparticular operations pursuant to instructions from program software.Algorithmic descriptions or symbolic representations are examples oftechniques used by those of ordinary skill in the signal processing orrelated arts to convey the substance of their work to others skilled inthe art. An algorithm is here, and generally, is considered to be aself-consistent sequence of operations or similar signal processingleading to a desired result. In this context, operations or processinginvolve physical manipulation of physical quantities. Typically,although not necessarily, such quantities may take the form ofelectrical or magnetic signals capable of being stored, transferred,combined, compared or otherwise manipulated. It has proven convenient attimes, principally for reasons of common usage, to refer to such signalsas bits, data, values, elements, symbols, characters, terms, numbers,numerals, or the like. It should be understood, however, that all ofthese or similar terms are to be associated with appropriate physicalquantities and are merely convenient labels. Unless specifically statedotherwise, as apparent from the discussion herein, it is appreciatedthat throughout this specification discussions utilizing terms such as“processing,” “computing,” “calculating,” “determining” or the likerefer to actions or processes of a specific apparatus, such as a specialpurpose computer, special purpose computing apparatus or a similarspecial purpose electronic computing device. In the context of thisspecification, therefore, a special purpose computer or a similarspecial purpose electronic computing device is capable of manipulatingor transforming signals, typically represented as physical electronic ormagnetic quantities within memories, registers, or other informationstorage devices, transmission devices, or display devices of the specialpurpose computer or similar special purpose electronic computing device.

In the preceding detailed description, numerous specific details havebeen set forth to provide a thorough understanding of claimed subjectmatter. However, it will be understood by those skilled in the art thatclaimed subject matter may be practiced without these specific details.In other instances, methods and apparatuses that would be known by oneof ordinary skill have not been described in detail so as not to obscureclaimed subject matter.

The terms, “and”, “or”, and “and/or” as used herein may include avariety of meanings that also are expected to depend at least in partupon the context in which such terms are used. Typically, “or” if usedto associate a list, such as A, B or C, is intended to mean A, B, and C,here used in the inclusive sense, as well as A, B or C, here used in theexclusive sense. In addition, the term “one or more” as used herein maybe used to describe any feature, structure, or characteristic in thesingular or may be used to describe a plurality or some othercombination of features, structures or characteristics. Though, itshould be noted that this is merely an illustrative example and claimedsubject matter is not limited to this example.

While there has been illustrated and described what are presentlyconsidered to be example features, it will be understood by thoseskilled in the art that various other modifications may be made, andequivalents may be substituted, without departing from claimed subjectmatter. Additionally, many modifications may be made to adapt aparticular situation to the teachings of claimed subject matter withoutdeparting from the central concept described herein.

Therefore, it is intended that claimed subject matter not be limited tothe particular examples disclosed, but that such claimed subject mattermay also include all aspects falling within the scope of appendedclaims, and equivalents thereof.

What is claimed is:
 1. A method of supporting location determination ofa user equipment (UE) performed by an entity in a wireless network, themethod comprising: determining an available portion of a wirelessspectrum by the entity, wherein the entity is one of a plurality ofranging sources for the UE, wherein the plurality of ranging sources forthe UE comprise a cluster of ranging sources that sequentially broadcastranging signals with no temporal overlap and using a same set ofchannels; generating a ranging signal over the available portion of thewireless spectrum; broadcasting the ranging signal to be received by theUE; and broadcasting a message with location information related to theranging signal.
 2. The method of claim 1, wherein the ranging signal isa wideband waveform comprising multiple channels.
 3. The method of claim2, wherein the multiple channels are contiguous.
 4. The method of claim2, wherein the multiple channels are not contiguous.
 5. The method ofclaim 1, wherein a first ranging signal in the sequentially broadcastranging signals includes an identification of the set of channels in apreamble that is determined by a first ranging source in the cluster ofranging sources.
 6. The method of claim 1, wherein the entity is a firstranging source in the plurality of ranging sources that sequentiallybroadcast ranging signals.
 7. The method of claim 6, wherein determiningthe available portion of the wireless spectrum comprises detectingenergy level for different channels in the wireless spectrum.
 8. Themethod of claim 6, wherein generating the ranging signal comprisesgenerating a preamble indicating a time over which the sequentiallybroadcast ranging signals will occur.
 9. The method of claim 1, whereinthe entity broadcasts the ranging signal after receiving a rangingsignal broadcast by a ranging source that immediately precedes theentity in the sequential broadcast of the ranging signals.
 10. Themethod of claim 9, wherein determining the available portion of thewireless spectrum comprises examining a waveform or a preamble of aranging signal from a preceding ranging source.
 11. The method of claim1, wherein the message with the location information related to theranging signal is broadcast in an Intelligent Transport System (ITS)spectrum.
 12. The method of claim 1, wherein the location informationcomprises at least one of a location of the entity, a sequenceidentifier indicating a position of the entity in the plurality ofranging sources for the UE, a time when the entity broadcasts theranging signal, or a combination thereof.
 13. The method of claim 1,wherein the entity comprises a road side unit or a vehicle.
 14. Anentity in a wireless network capable of supporting locationdetermination of a user equipment (UE) comprising: a wirelesstransceiver configured to broadcast signals to a UE in a wirelessnetwork; at least one memory; and at least one processor coupled to thewireless transceiver and the at least one memory, the at least oneprocessor configured to: determine an available portion of a wirelessspectrum by the entity, wherein the entity is one of a plurality ofranging sources for the UE, wherein the plurality of ranging sources forthe UE comprise a cluster of ranging sources that sequentially broadcastranging signals with no temporal overlap and using a same set ofchannels; generate a ranging signal over the available portion of thewireless spectrum; broadcast the ranging signal to be received by theUE; and broadcast a message with location information related to theranging signal.
 15. The entity of claim 14, wherein the ranging signalis a wideband waveform comprising multiple channels.
 16. The entity ofclaim 15, wherein the multiple channels are contiguous.
 17. The entityof claim 15, wherein the multiple channels are not contiguous.
 18. Theentity of claim 14, wherein a first ranging signal in the sequentiallybroadcast ranging signals includes an identification of the set ofchannels in a preamble that is determined by a first ranging source inthe cluster of ranging sources.
 19. The entity of claim 14, wherein theentity is a first ranging source in the plurality of ranging sourcesthat sequentially broadcast ranging signals.
 20. The entity of claim 19,wherein the at least one processor is configured to determine theavailable portion of the wireless spectrum by being configured to detectenergy level for different channels in the wireless spectrum.
 21. Theentity of claim 19, wherein the at least one processor is configured togenerate the ranging signal by being configured to generate a preambleindicating a time over which the sequentially broadcast ranging signalswill occur.
 22. The entity of claim 14, wherein the entity broadcaststhe ranging signal after receiving a ranging signal broadcast by aranging source that immediately precedes the entity in the sequentialbroadcast of the ranging signals.
 23. The entity of claim 22, whereinthe at least one processor is configured to determine the availableportion of the wireless spectrum by being configured to examine awaveform or a preamble of a ranging signal from a preceding rangingsource.
 24. The entity of claim 14, wherein the message with thelocation information related to the ranging signal is broadcast in anIntelligent Transport System (ITS) spectrum.
 25. The entity of claim 14,wherein the location information comprises at least one of a location ofthe entity, a sequence identifier indicating a position of the entity inthe plurality of ranging sources for the UE, a time when the entitybroadcasts the ranging signal, or a combination thereof.
 26. The entityof claim 14, wherein the entity comprises a road side unit or a vehicle.27. An entity in a wireless network capable of supporting locationdetermination of a user equipment (UE) comprising: means for determiningan available portion of a wireless spectrum by the entity, wherein theentity is one of a plurality of ranging sources for the UE, theplurality of ranging sources for the UE comprise a cluster of rangingsources that sequentially broadcast ranging signals with no temporaloverlap and using a same set of channels; means for generating a rangingsignal over the available portion of the wireless spectrum; means forbroadcasting the ranging signal to be received by the UE; and means forbroadcasting a message with location information related to the rangingsignal.
 28. The entity of claim 27, wherein the entity is a firstranging source in the plurality of ranging sources that sequentiallybroadcast ranging signals.
 29. A non-transitory computer readable mediumincluding program code stored thereon, the program code is operable toconfigure at least one processor in an entity in a wireless network userequipment (UE) for supporting location determination of a user equipment(UE), the program code comprising instructions to: determine anavailable portion of a wireless spectrum by the entity, wherein theentity is one of a plurality of ranging sources for the UE, theplurality of ranging sources for the UE comprising a cluster of rangingsources that sequentially broadcast ranging signals with no temporaloverlap and using a same set of channels; generate a ranging signal overthe available portion of the wireless spectrum; broadcast the rangingsignal to be received by the UE; and broadcast a message with locationinformation related to the ranging signal.
 30. The non-transitorycomputer readable medium of claim 29, wherein the entity is a firstranging source in the plurality of ranging sources that sequentiallybroadcast ranging signals.